Space between power tubes

[CarlyBoy]

Hey All,

Not much luck doing a search on this one..

Trying to decide what size chassis I need to buy. Besides the space for components inside, another factor is tube placement. Obviously the more space between tubes the better for keeping heat down, but can anyone offer a basic rule of thumb for minimum distance between power tubes (PL519s in my case - if tube type matters) so they have adequate cooling? Thanks!

[DigitalJunkie]

Sometimes the tube's datasheet will have guidelines for mounting clearance,but not always.

[Sherman]

If you can't find a recommendation on the data sheet then a rule of thumb seems to be 1x to 1.5x the tubes' envelope diameter. I've also seen that same range applied to the distance between output tubes and the OPT.

[Alastair E]

A recommendation for the very hot 6C33 by many who have experience of it, is 3 inches clearance. This tube has a rep of burning sockets though.....

The PL509 may not be quite as hot, but three inches should be quite enough without making the chassis too big, unless you plan an OTL with herds of tubes! ...

[Wavebourn]

According to convection laws no less than 8 mm between tubes. The more the better, but more significant is a good path for convection, i.e. free flow of the air from bottom to top. In this my tube amp project I designed it such a way so tubes also suck the air from transformer compartment:

[frank754]

Very nice look. wavebourn. It seems that the mesh also would keep the heat a bit separate between the tube / xfmr areas as well as hide the iron.
How did you design the side panels, is that just custom-cut sheet metal with padding & vinyl glued over it, or a fancier combo?
Looks great

[alexmoose]

this bit of thermodynamics (which I have been trying to figure out for a long time) really puts a damper on my plans for a Tube Amplifier/ bread toaster...

[Wavebourn]

Originally posted by frank754
Very nice look. wavebourn. It seems that the mesh also would keep the heat a bit separate between the tube / xfmr areas as well as hide the iron.
How did you design the side panels, is that just custom-cut sheet metal with padding & vinyl glued over it, or a fancier combo?
Looks great

Thank you!
It is made of an old wooden shelf covered by thin foam and leather imitation.
xformer area has grill on bottom of the rear panel, so air goes from rear to front. Also, you may see aluminum mirror under the front grill.

Originally posted by alexmoose
this bit of thermodynamics (which I have been trying to figure out for a long time) really puts a damper on my plans for a Tube Amplifier/ bread toaster...

Thermodynamics starts when criterium of Grasgoff and Prantle (I am not sure about English spelling) is reached and laminar flow becames turbulent one, so you'll hear a noise caused by flowing air.
Before that common sense matters.